Method and system for thermal analysis

ABSTRACT

A temperature programmed solid sample chamber adapted to apply thermal energy to a sample material. A carrier gas is flowed through the chamber whose temperature is raised at a programmed relatively slow rate to limit the thermal energy applied to the sample and thereby reduce the production of secondary decomposition products of the material under analysis. The effluent gases containing the decomposition products are swept through a first detector and thence through a first valve to vent. The valve is adjustable so that these effluent gases when desired may be stored in a cold trap. The stored gases are released from the trap by heating and reversing carrier gas flow through the trap and then passing the stored gases as a slug sample onto a chromatographic separating column for separation into their constituent components. The constituent components of the stored gases are then passed through a second detector. By recording the response of the two detectors, much information about the character and properties of the original material may be obtained.

United States Patent [191 Paul [ 1 Nov. 12, 1974 METHOD AND SYSTEM FOR THERMAL ANALYSIS [75] Inventor: Donald G. Paul, Kennett Square, Pa.

[73] Assignee: Chromalytics Corporation Unionville, Pa.

[22] Filed: Oct. 4, 1972 [21] Appl. No.: 294,836

[52] US. Cl 23/230 PC, 23/232 C, 23/253 PC, 73/6l.l C [51] Int. Cl. GOln 25/00, GOln 31/08 [58] Field of Search 23/230 PC, 253 PC, 230 R, 23/232 C; 73/23.l, 61.1 C; 55/386, 67;

OTHER PUBLICATIONS Garn, P. D., Talanta, 11, 1417-1432 (1964).

Solid Samples '0 Primary ExdminerRobert M. Reese Attorney, Agent, or FirmMortenson & Weigel [57] ABSTRACT A temperature programmed solid sample chamber adapted to apply thermal energy to a sample material. A carrier gas is flowed through the chamber whose temperature is raised at a programmed relatively slow rate to limit the thermal energy applied to the sample and thereby reduce the production of secondary decomposition products of the material under analysis. The effluent gases containing the decomposition products are swept through a first detector and thence through a first valve to vent. The valve is adjustable so that these effluent gases when desired may be stored in a cold trap. The stored gases are released from the trap by heating and reversing carrier gas flow through the trap and'then passing the stored gases as a slug sample onto a chromatographic separating column for separation into their constituent components. The constituent components of the stored gases are then passed through a second detector. By recording the response of the two detectors, much information about the character and properties of the original material may be obtained.

17 Claims, 10 Drawing Figures T amp. Pray D s zz'a z, D6586 Z0! I l l l l I l l l a a 14 2 Gms-lquid S 18.5 1

[ 23 m g3 Thermogram/ Ex Gas fllu'omioyrm Time/Tswynsz ahwe TTemperaizwe BACKGROUND OF THE INVENTION vides only certain information and is limited to volatile or gaseous compounds. Further, the volatiles in the samples under test often tend to react with the main decomposition products creating misleading information.

Outside of the field of pyrolysis many thermal methods have been described that detect or measure evolved gaseous products as a function of temperature. One such technique involves the use of a differential thermal analysis instrument in which the evolved gases are sampled and then detected using a gas chromatograph. This work was described by T. D. Garn in TALANTA, Vol. 11, pages 1,417 to 1,432, 1964. Among the disadvantages encountered with the Garn technique are the apparent inability to adequately trap and store the desired effluent gases, and the inability to store such evolved gases for later analysis when and as desired.

Still other techniques were devised by Jen Chiu and described in an article appearing in Analytical Chemistry, Vol. 40 pages 1,516 to 1,520, 1968. In this article, Chiu describes a system utilizing thermogravmetric analysis in which the effluent gases resulting from thermal heating are stored and then analyzed by a gas chr0- matograph. One of the problems encountered by Chiu included the inability to properly sense and select particular segments of the evolved gases for separate analysrs.

It is, therefore, an object of this invention to obviate many of the disadvantages of the prior art systems and methods for thermal analysis of materials.

Another object of this invention is to provide an improved system for the accurate thermal analysis of materials.

A still further object of this invention is to provide an improved more versatile method for the accurate thermal analysis of materials.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT and first carrier gas means for selectively passing said effluent gases from the thermal means through the first detector means to the trap means.

The system alsoincludes a column means for separating the stored gases into their constituent components, a second detector means for measuring a property of the constituent components, and additional carrier gas means for passing the stored gases through the column means and thence, after separation, into the constituent components, through the second detector means. This facilitates the intermittent analysis of the effluent gases. By carefully programming the rate at which the heat is applied to the sample under analysis, secondary decomposition products are reduced and the analyses performed thereby are more reproducible. Further, the

' volatiles contained in the sample can be separated from the decomposition products thereby permitting more accurate analyses since the volatiles and other impurities do not interact with the main decomposition products producing a former source of analytical errors.

According to the preferred method of the invention, the temperature of a sample under analysis is increased slowly and selected ones of the volatiles and other decomposition products resulting therefrom are swept through a detector and thence to a trap. The desired effluent gases and volatiles are trapped and stored for subsequent analysis by a chromatographic separating column. Finally, the selected ones of the stored gases are passed intermittently through the separating column, separated into their constituent components, and then detected.

BRIEF DESCRIPTION OF THE DRAWINGS The novel features that are considered characteristic of this invention are set forth with particularity in the appended claims. The invention, itself, however, both as to its apparatus and method, as well as additional objects and advantages thereof, will best be understood from the following description when read in connection with the accompanying drawings, in which:

FIG. 1 is a block diagram of a system capable of performing the method of this invention;

FIG. 2 is a flow schematic diagram of a system illustrating the preferred embodiment of this invention;

FIGS. 3A and B, respectively, are a thermogram and a chromatogram depicting typical results derived from pursuing the several steps of the method this invention; and

FIGS. 4, 5 and 6 each depict a chromatogram (FIGS. 43, 5B, 6B) and a thermogram (FIGS. 4A, 5A, 6A) resulting from further analytical steps employed in pursuing the method of this invention.

' DESCRIPTION OF THE PREFERRED METHOD AND SYSTEM According to the method of this invention a solid sample to be analyzed is placed in a thermal chamber 10 (FIG. 1) whose temperature may be raised at any desired rate as a function of time or maintained isothermally. The sample material thus undergoes thermal decomposition or volatilization. The resulting effluent gases, which include the decomposition products as well as the volatile components of the solid sample under analysis, are passed to a detector 12. The detector 12 may be any of the conventional well-known types of detectors. Preferably, however, a thermal conductivity or flame ionization type detector is used. Alternatively, a specific detector such as a flame photometric detector, electron capture detector or similar detector may be employed. In any event, the detector,

which measures some property of the effluent gases such as thermal conductivity, ionization, etc., provides an electrical output signal at the line 14 which may be plotted on a recorder (not shown) to provide a visual indication 16 of the signal amplitude (indicating the variations in amplitude of the particular property under test) as a function of either time or temperature as the casemay be. This resulting graph or waveform 16 is typically termed a thermogram.

These effluent gases as detected may then be passed to vent 18 until such time as it is desired to store a particular component or components of the effluent gases for further analysis. When such is desired, those selected gas components are stored in a trap 20 which may be nothing more than a conventional cold trap having heating elements to permit the rapid release by heat of the stored components. Alternatively, the trap may be packed with a standard gas chromatographic type packing, such as that sold under the trade name PORAPAK by Waters Associates, Inc. which is a polyaromatic resin comprising cross-linked polymers of polystyrene and resin or other well known packings utilized for this purpose.

When it is desired to further analyze these stored gas components, the trap is rapidly heated to release the storedcomponents generally as a slug sample. These stored components are then passed through a standard gas chromatograph separating unit 22 and the separated constituent components of the samples thus separated are then sensed by a second detector 24. This second detector may be similar to the first. The output signal from the second detector, in the form of an electrical signal on the line 26, may be recorded. The recorded signal, in this case from a gas chromatograph, is in the form of an amplitude varying signal as a function of time. The amplitude of the signal is plotted on a strip recorder as the ordinate with time/temperature as the abscissa to provide a resulting standard gas chromatograph recording as illustrated by the waveform 28.

In typical use, the sample to be analyzed is placed in a sample boat (not shown) and a carrier gas passed through the thermal analyzer chamber. Alternatively, the sample may be placed in a tube and the carrier gas flowed through the tube. The resulting released volatiles and other decomposition products are observed by the detector 12 and by viewing the thermogram 16 anindication as of the occurrence of the several gaseous decomposition components of the sample are observed. When a desired decomposition product or products is observed in the thermogram 16, these are immediately selectively stored in the trap 20 and held for further intermittent analysis. When ready for further analysis, the trap 20 is heated and the stored products selectively released and passed on to the gas chromatograph 22 for separation into its constituent components. These constituent components are sensed by the second detector 24 to produce the gas chromatogram 28 which is indicative of some of the properties of the sample under test. It is then apparent that one or more of the effluent decomposition gases may be stored. One or more of the stored gases may be intermittently separated into its constituent components for analysis.

This method has many advantages. For one, since minimal thermal energy is applied and applied slowly to break down the structure of the material under test,

the production of secondary decomposition products is reduced. Furthermore, the ultimate chromatograms are simple and are easily reproduced simply by duplicating the rate at which the heat applied to the sample. Impurities in the sample such as solvents, monomers, etc. can be trapped out prior to the heating of the main species. These solvents and the like may be analyzed directly by gas chromatography. Interaction among the impurities and main decomposition products is appreciably reduced by separately storing and analyzing them. With separate and/or low temperature storage, they have little chance of interacting. In addition, quantitative information on the various components in the sample, including polymer. blends and co-polymer compositions, in many cases, can be obtained directly from the thermogram alone. All or any part of the decomposition gases of a sample may be analyzed.

A further advantage of this method is that large sample sizes can be utilized for analysis of trace amounts of materials present in a large matrix. The desired trace materials are selectively trapped and thus separated from the effluent decomposition gases. The trace materials are then analyzed at will. In addition, small samples can also be introduced into the gas chromatograph by trapping only a small fraction of the decomposition products. In the case of the large sample sizes, the large samples are merely passed to vent whereas the trace amounts are trapped and stored for analysis. The temperature and the extent of each decomposition step is controlled and measured conveniently by the programmer and detector respectively. For that matter, both the effluent and residue of each thermal change can be recovered for studies by other analytical methods.

In accordance with an alternative embodiment of the method of this invention, the effluent gases from the thermal analyzer may be passed through a reactor for either hydrogenation, oxidation, or other chemical reaction prior to detection. This greatly facilitates catalytic kinetic type studies.

A preferred system capable of implementing the method described is illustrated in FIG. 2. In this figure, solid samples of material may be analyzed utilizing a sample chamber 30 which may be in the form of either a glass or quartz tube placed in a split ceramic oven, typically 2% by 1% by 1% inches, that is temperature programable from room temperature to 800 C. The

temperature of the sample chamber 30 may be controlled by a suitable temperature programmer 32 connected to the sample chamber 30 through the wire leads denoted by the dashed line 34. The temperature programmer may be any suitable temperature programmer capable of sensing the temperature in the sample chamber and controlling such temperature by the appropriate application of heat thereto. The sample chamber 30 may contain a position for a small sample boat in which the sample material is held during heating. Upon heating, the volatile components in the sample material, as well as the decomposition products emitted in the form of effluent gases, are swept from the sample chamber 30 by the flow of a suitable carrier gas such as helium or other gas supplied by a source illustrated by the cylinder 36. Reactive gases such as oxygen or hydrogen could also be used. The carrier gas is supplied through a suitable flow controller 38 and rotameter 40,.if desired, to control and regulate the flow through the sample chamber.

To handle liquid samples, an, injection port 31 may be positioned in front of the sample chamber and the carrier gas flowed through it. Any conventional injection port may be used.

The outlet of the sample chamber 30 is connected by suitable conduits to the first port 42 of a two position,

four port valve 44. The valve rotor (not shown) is illustrated in its first position with the arcuate lines indicating which ports are interconnected. The second position of the valve is established by a 90 rotation of the valve. Each of the valves preferably are constructed of stainless steel and have a filled plastic rotor preferably made of TEFLON a trademark of E1. duPont de Nemours & Co., Inc., a polytetrafluoroethylene resin or other suitable self-lubricating plastic. Valves of this type are commercially available. The e ma1n1ng= ports of the first valve are numbered in a clockwise sense 46, 48 and 50. In the first valve position, as illustrated, the first and second ports 42 and 46 are connected together and the third and fourth ports 48 and 50 are connected together for fluid flow. In the second position of the first valve the second and third ports 46 and 48 are connected together as are the first and fourth ports 42 and SUIThe second port 46 of the first valve is connected to the first port 52 of a second, two position, four port valve 54. The remaining ports of the second valve 54 are illustrated as the second port 56, third port 58 and the fourth port 60. In its first position, the first and sec ond ports 52 and 56 are interconnected as are the third and fourth ports 58 and 60. In the second position of the second valve, the first and fourth ports 52 and 60 are interconnected as are the second and third ports 56 and 58.

To complete the connections for the first valve 44, the third port is connected by conduit to a conventionalgas/liquid injection port 62 of conventional design as typically used in chromatography. The injection port is connected to have a carrier gas flow therethrough from the carrier gas supply 36 through the conduit 64. A suitable flow controller 38 and rotameter 40 connected serially in the conduit 64 are also used if desired.

The third and fourth ports of the second valve 54 are connected to either end of a reactor 68. This reactor may be any suitable type of reactor packed or otherwise and' capable of being heated as is available on the market. It may be adapted to provide, for example, either oxidation, hydrogenation or other suitable chemical reaction as may be desired for use in catalytic and other thermal reaction studies, as will be described. Thus, in the first position of the second valve, the reactor 68 is closed off from the system with the effluent from the sample chamber passing directly through the first valve 44 and the second valve 54.

i The second port 56 of the second valve 54 is connected to one side of a conventional thermal conductivity detector 70. Instead of a thermal conductivity detector other suitable detectors capable of measuring some property of the gases flowing therethrough, may be employed. For example, a flame ionization detector or a specific detector such as an electronic capture or a flame photometric detector may be employed. In fact, in a preferred embodiment of the invention, as is illustrated, a flame detector 71 is connected to the second port 56 along with the thermal conductivity detector. From the output of the thermal conductivity detector 70 the gas flowis connectedto the first port 72 of a third valve 74. The third valve 74 is a two position. six port valve of the same general construction as the first and second valves with the exception of the increased number of ports. Adjacent pairs of the ports 72, 76, 78, 80, 82 and 84 may be interconnected by manipulation of the rotor. Although rotary valves are illustrated, it is to be understood that plunger types or other switching valves may also be used. In the first position of the third valve, the first port 72 is interconnected with the second port 76. In like manner, the third and fourth ports 78 and are interconnected as are the fifth and sixth ports 82 and 84. In the second position of the third valve, the second and third ports 76 and 78 are interconnected as are the fourth and fifth ports 80 and 82 as are the first and sixth ports 72 and .84. The second port 76 of the third valve is connected through a suitable conduit to a trap 86 and thence to the fifth port 82. The sixth port 84 is connected to vent to the atmosphere. Carrier gas from the supply 36, preferably connected through a suitable flow controller 38 and rotameter 40, is connected to the fourth port 80. In similar manner, the third port 78 is connected through a suitable conduit to a conventional gas chromatographic separating column 88. The trap 86 may be any suitable type of conventional trap and may, for ex ample, simply be a cold trap or may be a column filled with suitable packing as described hereinbefore. The trap is also preferably wrapped with a heating element such that an operator can switch on the heater to provide a slug release of the sample trapped therein.

The first, second and third valves 44, 54 and 74 together with the detector 70 are all enclosed within an oven 90 to maintain the valves, the detector and their interconnecting conduits suitably heated to avert condensation of the effluent gases and other volatiles from the sample chamber 30. The gas chromatographic separating column 88 also is enclosed within a conventional gas chromatograph oven 92 which preferably is temperature programmable. In this instance the temperature programmer 32 may be used to temperature program the gas chromatograph oven 92 as well as the sample chamber 30 since the two generally are not used at the same precise points in time. If desired, however, separate temperature programmers may be used.

The outlet of the column 88 is connected from the oven 92 and through the second side or cell of the thermal conductivity detector 70 and thence out to vent. In addition, the outlet of the column 88 is also connected to the flame detector. In alternative embodiments, this outlet vent 94 may be connected to other analyzers such as a mass chromatograph, mass spectrometer, infrared spectrometer and the like. Both of the cells of the detector 70 provide an electrical output signal which is connected through suitable wiring to a recorder 102, having two recording pens. The first pen is connected to record the thermogram 104 which is the detected output signal from the first cell of the detector 70 representing a property of the effluent from the sample chamber 30. The second pen records a conventional chromatogram 106 which is the electrical output from the second cell of the detector 70 detecting a property in the output from the separating column 88 and represents the constituent components of the separated decomposition products as will be described. A]- ternatively, a single pen recorder may be used. In this instance the same bridge circuit is used for both sides of the thermal conductivity detector with a polarity reversing switch being interposed between the bridge and the recorder to provide the correct polarity of electrical signal to the recorder.

It is thus possible using this system to observe all or part of the effluent gases observed on the thermogram intermittently, separate them into their constituent components, and observe the individual constituents of any portion of the effluent gases. By way of definition, a thermogram is a curve describing a property of the evolved gases versus temperature or time as opposed to a gas chromatogram which is a curve describing a property of all or a portion of the constituent components of the evolved gases as a function of temperature or time.

In constructing the system illustrated in FIG. 2, the injection ports 31 and 62 typically are-maintained at any isothermal temperature selected. The valve and de tector oven 90 is maintained at any isothermal temperature within the limits permitted by the detector and valve materials. The trap heater should be adjustable to cut-off at any temperature up to typically 500 C. The reactor is isothermally adjustable at any temperature typically up to 800 C. The temperature programmer 32 typically should provide for isothermal or program temperature operation up to 800 C. These temperature limits are typical only and can be higher if desired. All connecting conduits and transfer conduits are heated preferably to avoid condensation and are formed of stainless steel. Preferably, a gold line should connect to and extend from the sample chamber to avoid catalytic reactions.

In a typical use of the system illustrated, the first, second and third valves are all positioned in the first position as illustrated in FIG. 2 and a solid sample is placed in a boat in the sample chamber 30 within the tube forming the sample chamber and the temperature programmer started. Carrier gases are started flowing and the operator adjusts the several rotameters and flow controllers to the desired flow rates. As the temperature in the sample chamber 30 increases, various volatiles are passed through the first and second rotary valves 44, 54 and detected in the first cell of the detector 70 which can be observed on the thermogram waveform of FIG. 3A in which signal amplitude is plotted as the ordinant versus temperature as the abscissa. These volatiles and effluent gases resulting from the decomposition of the solid sample are connected and stored in the cold trap 86 for later use. Alternatively, the third valve could have been switched to its second position to vent the volatiles and then switched back to its first position to trap intermittently portions of the effluent gas. When the run is finished and the thermogram complete, the third valve 74 is switched to its second position and the temperature programmer is switched over to control the gas chromatographic oven. The trap heater is now switched on by a switch (not shown) such that the volatiles and effluent gases are boiled off or released from the trap as a slug sample. The carrier gas flowing through the trap '86 is reversed, upon the switching of the valve 74, in direction so that these volatiles and effluent gases are back flushed out of the trap and directed through the separating column 88 where they are separated in a conventional manner. The separatedconstituent components of the volatiles and other effluent gases are detected in the second side of the de tector 70 to produce the chromatogram illustrated in FIG. 33 having a plurality of peaks 120 each corresponding to one or more of the volatiles and effluent gases of the original sample.

After the run is complete, the operator now has the option of observing the various portions of the volatiles and effluent gases individually. He may selectively pass unwanted volatiles to vent rather than storage. He may selectively and intermittently pass the stored gases through the separating column 88 for further analysis. For example, as illustrated in the thermogram of FIG. 4A one can examine only the effluent gases released during the analysis as depicted by the first temperature plateau 122 (FIG. 3A) of the thermogram. To accomplish this, a second sample of the same material is placed in the sample chamber and the analysis run as before. In this instance, however, the operator observes the thermogram being traced and when the end of the temperature 122 is reached, he switches the first valve 44 to the second position such that the remainder of the effluent gases from the sample are passed out to vent. The vents can be used as alternate trapping positions if so desired. The carrier gas through the second conduit 64 sweeps up through the second and third ports of the first valve 44 to sweep the already evolved effluent gases on through the detector and into the trap 86 for storage. To analyze the stored gases, the trap is heated and back flushed by switching the third valve 74 to its second position and the effluent gases represented by the first plateau 122 of the thermogram are now analyzed separately in the gas chromatograph. In this instance it may be noted that the corresponding chromatogram by way of illustration has only two peaks 124 as illustrated in FIG. 4B. Thus, of the several peaks depicted by chromatogram in FIG. 38, only portions of two are seen to have been the result of the lower temperature decomposition.

For the next run, a third sample is prepared and the procedure run as before. In this instance, however, the third valve 74 is maintained in its second position with the effluent gases passing to vent until the second characteristic portion 126 of the thermogram depicted in FIG. 5A is indicated on the recorder 102. At this point the third valve is switched to its first position such that the effluent gases corresponding to this portion of the thermogram are passed into the trap 86 for storage. When the end of this temperature cycle represented by the portion of the thermogram designated 124 is reached, the third valve is again returned to its second position to vent the remainder of the effluent gases. When the sample run is complete and the remaining effluent gases passed out to vent by the third valve 74, the third valve is again returned to its second position and heat is applied to the trap 86 such that the stored effluent gases are back flushed out of the trap 86 into the separating column 88 to provide the chromatogram illustrated in FIG. 5B, which in this case, by way of illustration, depicts only two peaks 128. One can readily determine which peak or peaks of the original chromatogram 120 are formed by the effluent gases produced during the second phase 126 of the temperature cycle.

Finally, a fourth run is made to analyze effluents occurring during the third characteristic portion of the heating cycle as represented by portion 130 of the thermogram. The same procedure is followed with the third valve being in a second position to direct all detected effluent gases to vent until those effluent gases corresponding to the third characteristic portion (FIG. 6A)

130 of the thermogram arrive. At this time the third valve is switched to its first position such that these effluent gases may be trapped. Upon completion of the run, the third valve is again returned to its second position for back flushing and analysis of the stored effluent gases by the gas chromatograph. This results in the chromatogram depicted by the peaks 132 in FIG. 68 corresponding to the effluent gases evolving during that portion of the heat cycle depicted by portion 130 of the thermogram. Here again, the operator can by examination of the several thermograms and chromatograms obtain significant information about the material under test.

Instead of using a new sample for the second and later runs, the temperature programming of the sample chamber may be stopped at the appropriate points on the thermogram, and then resumed at will to obtain the effluent gases corresponding to the different portions 122, 126, and 130 of the thermogram.

If a liquid or gas sample is to be used, it may be injected through the injection port 62 by switching the first valve to its second position. In like manner, any given sample may be passed through the reactor 68 by switching the second valve to its second position. Also, a liquid sample may be introduced into the sample chamber 30 for thermal decomposition using the injection port 31.

The following table depicts some of the many variations in analytical procedures possible using this systemuln this chart, according to the position of the three valves 44, 54 and 74, the various operating functions may be achieved as indicated.

Valve-No.

44 54 74 Operating Function A-position l l l A solid sample is heated and the effluent detected and trapped. A portion or all of the effluent can be vented by turning the third valve to the second position.

The flow is reversed through the trap and it is heated to drive the collected material onto the gas chromatographic column for analysis.

Asolid sample is heated and the effluent passed through a reactor (hydrogenation, etc.) prior to detection and trapping.

A gas or liquid sample can be introduced into the traps for subsequent gas chromatographic analysis.

A gas or liquid sample can be passed through a reactor (hydrogenation, thermal cracking, etc.) prior to trapping. The reacted species can then be analyzed by gas chromatography.

B-position l l 2 C-position i 2 l D-position 2 l l E-position 2 2 I There has thus been multitude a highly versatile analysis system capable of providing a multitide of functions. This system has particular advantages in that by applying heat slowly to the sample, the secondary decomposition products are reduced. Also by the slow application of heat the resulting analyses are more reproducible. Furthermore, it permits the ready separation of volatiles from the other decomposition products. By the use of thermal conductivity or flame detectors or other specific detectors highly sensitive results are obtained. Any portion or portions of the decomposition or effluent gases may be intermittently analyzed by gas chromatography or other instrumentation.

It will be obvious that various modifications may be made in the apparatus and in the manner of operating it. It is intended to cover such modifications and changes as would occur to those skilled in the art, as far as the following claims permit and as far as consistent with the state of the prior art.

What is claimed is:

l. A system for the thermal analysis of materials comprising:

thermal means for subjecting said materials to heat thereby to produce effluent gases,

first detector means coupled to said thermal means for measuring a property of said effluent gases, trap means coupled to said first detector means for storing said effluent gases,

first carrier gas means coupled to said thermal means for selectively passing said effluent gases from said thermal means through said first detector means to said trap means,

column means coupled to said trap means for separating said stored gases into their constituent components,

second detector means coupled to said column means for measuring a property of said constituent components, and

additional carrier gas means coupled to said trap means for selectively passing said stored gases from .said trap means through said column means and thence, after separation into said constiuent components, through said second detector means, thereby to permit the intermittent analysis of said effluent gases.

2. A system according to claim 1 which also includes temperature control means connected to said thermal means for varying the temperature of said materials as a function of time, thereby to limit the thermal energy applied to said materials to reduce the production of secondary decomposition products.

3. A system according toclaim 1 which also includes:

ples of said materials and exposing said materials to a flow of a carrier gas from said first carrier gas means while being heated.

6. A system according to claim 1 which also includes:

temperature control means connected to said thermal means for varying the temperature of said materials as a function of time thereby to limit the thermal energy .applied to said materials to reduce the production of secondary decomposition products, and

first valve means connected to said additional carrier gas means, said column means, and said trap means for selectively passing said effluent gases to said trap means and said stored effluent gases to said column means, said first valve means being a two position, six port valve.

7. A system according to claim 1 which also includes:

tional thermal means for varying the temperature of said column means as a function of time, a further carrier gas means for transporting fluid samples, and

second valve means connected to said thermal means, said first detector means, and said further carrier gas means for selectively passing said fluid samples and said effluent gases to said first detector means.

8. A system according to claim 1 which includes first valve means connected to said additional carrier gas means, said column means, and said trap means for selectively passing said effluent gases to said trap means and said stored constituents to said column means.

9. A system according to claim 8 wherein said first valve means is a two position, six port valve.

10. A system according to claim 1 which also includes:

a further carrier gas means selectively coupled to said first detector means for transporting fluid samples to said first detector means, and

second valve means connected to said thermal means, said first detector means, and said further carrier gas means for selectively passing said fluid samples and said effluent gases to said first detector means.

11. A system according to claim 10 which also includes a reactor and third valve means connected to said reactor, said first detector, and said second valve 12 means for selectively passing said effluent gases and said fluid samples through said reactor prior to passage to said first detector.

12. A method for thermally analyzing materials using a trap and separating column comprising the steps of:

heating said materials thereby to produce effluent decomposition gases,

measuring a property of said effluent gases,

passing selected ones of said effluent gases to said trap for storing said selected ones of said effluent gases,

intermittently passing at least one of said stored gases through said separating column to separate said stored gases into constituent components, and measuring a property of said constituent components.

13. A method according to claim 12 wherein only selected ones of said stored gases are passed through said separating column.

14. A method according to claim 12 which includes the additional step of varying the heat applied to said material as a function of time thereby to limit the thermal energy applied to said materials to reduce the production of secondary decomposition products.

15. A method according to claim 14 which includes the additional step of comparing variations in the measured property of said effluent gases as a function of time with variations in the measured property of said constituent components.

16. A method according to claim 14 which includes the additional step of selecting the effluent gases to be stored in accordance with the measured property of said effluent gases.

17. A method according to claim 14 which includes the additional steps of:

selectively introducing fluid sample materials fo measuring a property thereof,

selectively chemically reacting said fluid sample materials and said effluent gases thereby to produce reaction gases, and

measuring a property of said reaction gases.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3,847 546 Dated jnvs-mberjZ, 1074 lnvent fl Donald G. Paul It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In Column 9, line 57, after "thus been" delete "multitude" and insert--described-.

(333531;) attest:

C. D'AXN R C. lit-".5" Commissioner of Patents attesting Crificer and Trademarks ORM PO-IOSO (IO-59) USCOMM'DC 50376-P59 U.$. GOVERNMENT PRINTING OFFICE "I! O-IQI-SSI, 

1. A SYSTEM FOR THE THERMAL ANALYSIS OF MATERIALS COMPRISING: THERNAL MEANS FOR SUBJECTING SAID MATERIALS TO HEAT THEREBY TO PRODUCE EFFLUENT GASES, FIRST DETECTOR MEANS COUPLED TO SAID THERMAL MEANS FOR MEASURING A PROPERTY OF SAID EFFLUENT GASES, TRAP MEANS COUPLED TO SAID FIRST DETECTOR MEANS FOR STORING SAID EFFLUENT GASES, FIRST CARRIER GAS MEANS COUPLED TO SAID THERMAL MEANS FOR SELECTIVELY PASSING SAID EFFLUENT GASES FROM SAID THERMAL MEANS THROUGH SAID FIRST DETECTOR MEANS TO SAID TRAP MEANS, COLUMN MEANS COUPLED TO SAID TRAP MEANS FOR SEPARATING SAID STORED GASES INTO THEIR CONSTITUENT COMPONENTS, SECOND DETECTOR MEANS COUPLED TO SAID COLUMN MEANS FOR MEASURING A PROPERTY OF SAID CONSTITUENT COMPONENTS, AND ADDITIONAL CARRIER GAS MEANS COUPLED TO SAID TRAP MEANS FOR
 2. A system according to claim 1 which also includes temperature control means connected to said thermal means for varying the temperature of said materials as a function of time, thereby to limit the thermal energy applied to said materials to reduce the production of secondary decomposition products.
 3. A system according to claim 1 which also includes: additional thermal means for applying heat to said column means, and temperature control means coupled to said additional thermal means for varying the temperature of said column means as a function of time, thereby to facilitate the separation of said stored gases.
 4. A system according to claim 1 wherein said trap means includes heater means for heating said trap means, thereby to intermittently release said stored gases for passage to said column means.
 5. A system according to claim 1 wherein said thermal means includes a sample chamber for holding samples of said materials and exposing said materials to a flow of a carrier gas from said first carrier gas means while being heated.
 6. A system according to claim 1 which also includes: temperature control means connected to said thermal means for varying the temperature of said materials as a function of time thereby to limit the thermal energy applied to said materials to reduce the production of secondary decomposition products, and first valve means connected to said additional carrier gas means, said column means, and said trap means for selectively passing said effluent gases to said trap means and said stored effluent gases to said column means, said first valve means being a two position, six port valve.
 7. A system according to claim 1 which also includes: temperature control means connected to said thermal means for varying the temperature of said materials as a function of time, thereby to limit the thermal energy applied to said materials to reduce the production of secondary decomposition products, ADDITIONAL thermal means for applying heat to said column means, temperature control means coupled to said additional thermal means for varying the temperature of said column means as a function of time, a further carrier gas means for transporting fluid samples, and second valve means connected to said thermal means, said first detector means, and said further carrier gas means for selectively passing said fluid samples and said effluent gases to said first detector means.
 8. A system according to claim 1 which includes first valve means connected to said additional carrier gas means, said column means, and said trap means for selectively passing said effluent gases to said trap means and said stored constituents to said column means.
 9. A system according to claim 8 wherein said first valve means is a two position, six port valve.
 10. A system according to claim 1 which also includes: a further carrier gas means selectively coupled to said first detector means for transporting fluid samples to said first detector means, and second valve means connected to said thermal means, said first detector means, and said further carrier gas means for selectively passing said fluid samples and said effluent gases to said first detector means.
 11. A system according to claim 10 which also includes a reactor and third valve means connected to said reactor, said first detector, and said second valve means for selectively passing said effluent gases and said fluid samples through said reactor prior to passage to said first detector.
 12. A method for thermally analyzing materials using a trap and separating column comprising the steps of: heating said materials thereby to produce effluent decomposition gases, measuring a property of said effluent gases, passing selected ones of said effluent gases to said trap for storing said selected ones of said effluent gases, intermittently passing at least one of said stored gases through said separating column to separate said stored gases into constituent components, and measuring a property of said constituent components.
 13. A method according to claim 12 wherein only selected ones of said stored gases are passed through said separating column.
 14. A method according to claim 12 which includes the additional step of varying the heat applied to said material as a function of time thereby to limit the thermal energy applied to said materials to reduce the production of secondary decomposition products.
 15. A method according to claim 14 which includes the additional step of comparing variations in the measured property of said effluent gases as a function of time with variations in the measured property of said constituent components.
 16. A method according to claim 14 which includes the additional step of selecting the effluent gases to be stored in accordance with the measured property of said effluent gases.
 17. A method according to claim 14 which includes the additional steps of: selectively introducing fluid sample materials for measuring a property thereof, selectively chemically reacting said fluid sample materials and said effluent gases thereby to produce reaction gases, and measuring a property of said reaction gases. 